Thermocolor ribbon

Abstract

The color transfer density of a thermocarbon ribbon can be improved by forming the wax phase of a melt color layer of such a ribbon so that it contains a paraffin with a hardening temperature of about 50 to 110° C. and at least one ethylene-vinylacetate wax forming a eutectic with a paraffin.

We claim: 
     
       1. A thermocarbon ribbon comprising a thermocarbon ribbon carrier and a melt color on one side of said carrier, said melt color containing a pigment and a wax phase in which said pigment is distributed, said wax phase comprising 40 to 90 weight percent of a paraffin with a hardening temperature of about 50° to 110° C. and 10 to 60 weight percent ethylene-vinylacetate wax which forms a eutectic with the paraffin, said ethylene-vinylacetate wax having a melting point of about 87° to 92° C., a hardening point of about 83° to 92° C., a mean molecular weight of about 6500 to 7000 and a vinylacetate content of about 9 to 11 percent by weight. 
     
     
       2. The thermocarbon ribbon defined in claim 1 wherein said pigment is carbon black. 
     
     
       3. The thermocarbon ribbon defined in claim 2 wherein said melt color further includes at least one component capable of improving flow of the melt color during thermal printing and selected from the group which consists of ester wax, modified hydrocarbon resins and mixtures thereof. 
     
     
       4. The thermocarbon ribbon defined in claim 1 further comprising an adhesive layer on said melt color for improving transfer of the melt color during thermal printing and consisting of a paraffin and a tackifying resin.